Turtle Fur Lectra Sox Wader Socks, Electric Battery Heated Socks, Maroon Other Size: XS/S fits Men's 5-8.5 & Women's 6-10 - Medium fits Men's 9-10.5 & Women's 10.5-12 - L/XL fits Men's 11+ Wool blend (17% Wool) heated socks provide 6-8 hours of warmth. Uses "D" cell batteries (not included). Detached battery pouch can be worn on a belt or put in a pocket. Great for hunting, ice fishing, hiking, and sporting events. Won't shock, even when wet! The Lectra Sox are designed to keep feet warm, but not hot. Engage the heat only after you begin to feel the cold. Maximum benefit will be obtained by turning the socks off and on often.